Baseline Offset
Accelerometer calibration defines the process of identifying and correcting systematic measurement errors in motion sensors. The parameter zero g bias represents the output of an accelerometer when it is subjected to no acceleration or gravity. This value must be measured and subtracted to ensure accurate velocity and position estimates.
Cause Profile
Internal stresses from the packaging and tiny imperfections in the silicon microstructure generate this initial offset. During assembly, the solder cooling process can also bend the sensor chip slightly, altering the resting capacitance or resistance. This error is unique to each individual sensor, requiring custom correction for every manufactured unit.
Drift Effect
Over time, the bias shifts due to temperature changes and material aging, which can cause significant errors in navigation calculations. When the output has a steady offset, integrating it twice to calculate position leads to a quadratic error that grows rapidly. This drift is the primary limitation for inertial navigation systems.
Compensation Routine
Metrologists determine this value by placing the sensor in various orientations where the sensitive axis is perpendicular to gravity. In this position, the expected acceleration is zero, allowing any measured output to be recorded as the bias. Modern systems integrate automatic calibration routines that update this value whenever the device is detected to be at rest.
This field-level adjustment ensures that small shifts in the offset do not degrade the performance of the navigation system over time.
